1. Field of the Invention
The present invention relates to a systems and methods for sealing trunnions, and more particularly to systems and methods for sealing trunnions of ball tube mills for pulverizing materials.
2. Background of the Related Art
Ball tube mills are used in material size reduction processes, such as grinding coal or other minerals. A typical ball tube mill includes a large, cylindrical drum that rotates along its axis, supported by a trunnion on each end. As the drum rotates, a mass of balls and coal or other material mix in the bottom of the drum, which reduces the particle size of the coal or other material. Particles that are fine enough become airborne and are vented out of the drum for use in further processes such as coal combustion. New coal or other material enters through the ends of the drum to replace the airborne particles leaving the ends of the drum.
In order to move material between the rotating drum and related stationary components such as a coal piping system, for example, the rotating drum typically connects at each end to a stationary inlet/outlet box via a trunnion seal. The trunnion seal allows passage of material between the rotating drum and the stationary inlet/outlet box while discouraging or preventing material from escaping into the surroundings. It is advantageous to form the best possible seal between stationary and rotating components, as the fine particles involved can readily escape if the seal is inadequate. When operating a ball tube mill, the trunnion seals wear down and eventually need to be replaced. This can be exacerbated by the fact that the rotating axis of the mill tends to move downward as its bearings wear with use. Replacing the trunnion seals typically requires removing the inlet/outlet box from foundation blocks under the trunnions, which results in significant downtime.
Such conventional methods and systems generally have been considered satisfactory for their intended purpose. However, there still remains a continued need in the art for a trunnion seal that has an improved service life and is easier to install and remove. The present invention provides a solution for these problems.